fix: cert verify test fix

[jouho]

Resolved issues:

Resolves #4431

Description of changes:

• Previously, a test case was not running due to missing #include "crypto/s2n_rsa_pss.h". This is now added so the corresponding test is running.

• One of the test cases were failing even if the tests were enabled and this change fixes it. Specifically, the test was failing on calling s2n_tls_cert_verify_send() because The test runs in a for-loop with different configuration. The first iteration uses s2n_ecdsa_sha256 as signature scheme for the test and the second iteration uses s2n_rsa_pss_pss_sha256 as the signature scheme. The first iteration passes, but the second iteration fails because we're always setting test_scheme.sig_alg = S2N_SIGNATURE_ECDSA; this causes mismatch with RSA_PSS_PSS when sending cert_verify.

• Negative test cases were using a single connection object to send and receive cert_verify message. This is an incorrect set up as we do not want to introduce another source of failure other than the ones we are explicitly testing,. Therefore the tests are modified to use two connections (sending_conn and verifying_conn) to properly simulate the test cases

• In order to get better test result, change EXPECT_FAILURE() calls to EXPECT_FAILURE_WITH_ERRNO() with specific error to expect in each test case

• Clean up code to reduce redundancy and improve readability

Call-outs:

Testing:

Confirmed s2n_tls_cert_verify_test now runs all tests and passes all cases

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[maddeleine]

It looks like this test is no failing when we build with FIPS-validated libcryptos? You'll need to investigate that.